The potential digestibility of leaf and stem fractions of Rhodes grass (Chloris gayana) and Pangola grass (Digitaria decumbens) were determined by incubating in vitro with rumen fluid for 4, 7, 11 and 14 days with reinoculation after 7 days. The mean drymatter solubility (DMS) of four leaf and four stem samples from the two species, increased from 53·6% after 4 days to 63·8% after 14 days with increases of 14·9 and 5·7% for leaf and stem respectively. Prolonged incubation of sheep faeces from these feeds gave similar patterns of DMS as those for the original feed.

To determine the cause of the observed rise in DMS, leaf and stem of Rhodes grass was incubated for 21 days with rumen fluid and Onozuka cellulase. When using cellulose, DMS increased by 7·7% compared with 14·6% when using rumen fluid. The higher DMS with rumen fluid was associated with an increase in the mean disappearance of lignin from 33·6% at 4 days to 52·6% after 21 days. After 14 days there was no further loss of lignin from most samples indicating the existence of a hard resistant lignin core.

It was concluded that when determining potential digestibility forages must be incubated with rumen inoculum for at least 21 days and that shorter incubation times may lead to biased conclusions.

The 32 combinations of applying or not applying nitrogenous fertilizer on five dates, with 6-week intervals between dates, during one treatment year were compared in three field experiments with Italian ryegrass (Lolium mvltiflorum). Phosphorus (P)and potassium (K) were applied at a uniform, high rate to all plots. All plots were harvested, by cutting, five times during the treatment year and once in May of the subsequent year.

Dry-matter yields and dry-matter yield responses to N were lower at the September and October harvests than at the May, June and July harvests. Where no N was applied 6 weeks before a harvest, N applied 12 weeks before that harvest generally increased yields of dry matter, N, P and K. On the other hand, where N was applied 6 weeks before a harvest, N applied 12 weeks before that harvest tended not to increase dry-matter yield and tended to reduce P and K yields. Applying 420 kg N/ha/year compared with nil approximately trebled the amounts of dry matter, P and K harvested in the treatment year. At the May harvest in the subsequent year dry-matter yield was increased by N applied in the treatment year, for all five application dates, although the previous autumn there had been no positive residual effect of the early applications. Apparent recovery of N was low compared with that recorded with Italian ryegrass in Cambridge. The content of N, as well as P and K, in herbage in May was reduced by the application of N the previous year. In the 1972 experiment the proportion of ‘stem’ in the harvested produce was markedly increased by N application. The size of this effect may have been associated with the rather small amount of soil N available. Applied N increased the number of tillers in the sward, but this effect appeared to be rather short-lived. A major reason for the positive effect of applied N on dry-matter yield, including the positive residual effect, appeared to be the increase in leaf blade length and probably sheath length due to N.

Pulverized fuel ash and fiuidized combustor ash were used to modify the availablewater capacity and moisture characteristics of a gravelly sandy loam soil in a study of the effects of fine-particle amendments on crop yield. Intimate incorporation of the ashes into the top-soil at rates of up to 502 t/ha increased the available water retained in the surface 0·3 m of soil by 40–80 %. The increase was mainly water held at potentials of between –0·05 bar and – 1 bar.

Two sugar-beet crops followed by broad beans, salad onions and cabbage were grown in the amended soil. With the highest rate of ash addition yield of the onions was increased by over 30% and of the cabbages by 14%. No improvement in sugar-beet or broad-bean yields resulted from the treatment. Poor growth of the second sugar-beet crop was attributed to a reduced aeration effect but it is suggested that the failure of the increased available water to improve yield consistently in this and a previous experiment was in part caused by rapid evaporative losses from the amended soil.

The feasibility of enhancing cotton (Gossypium hirsutum L.) growth and nutrient uptake with Temik aldicarb was investigated using sand culture with a continuous flow of 1/5 strength of Hoagland solution. Aldicarb was incorporated in the nutrient solution at different rates, and was applied to the plants when they were 30 days old for a period of 1, 3, 5, or 7 days. The cation exchange capacity of the fresh roots of treated plants as well as the ionic permeability of the untreated plants as influenced by aldicarb application were also studied. Low rate of aldicarb provided a stimulus effect on the plant and enabled it to grow faster and to take up more N, P, K, Ca, Mg, and Na than the control. This suggested a direct effect of aldicarb on mineral metabolism especially those processes involving N and P. Maximum dry-matter yield and nutrient uptake occurred at the 5 mg aldicarb rate for all times of treatments. At a rate of 7middot;5 mg aldicarb, growth and nutrient uptake were inhibited, suggesting a toxicity of assimilatory processes within the plant which might have reduced its ability to take up and assimilate nutrients. Aldicarb facilitated the transfer of Na to the stem and leaves resulting in a more uniform distribution of Na throughout the treated plants compared with the control.

An experiment begun in 1956 and using a five-course rotation of barley, grass-clover ley, potatoes, wheat and kale and a block of permanent grass was continued.

N decreased yields of the rotation ley, slightly increased yields of potatoes (after the ley), but greatly increased yields of wheat, barley and kale and permanent grass. P increased the yields of all arable crops, of kale dramatically, but not of permanent grass. K greatly increased yields of wheat and the rotation ley and even more of potatoes, but it increased yields of barley, kale and permanent grass little.

F.Y.M. increased the yields of all crops; potatoes responded most. Applying fertilizers with the F.Y.M. diminished its effects, but except for wheat and barley grain a combination of the two produced the largest yields.

Mean yields from all combinations of N, P and K were a little smaller between 1961 and 1965 than between 1956 and 1960, and the yields were maintained best by applying F.Y.M. and fertilizers together. Responses to N and to K were similar in both rotations, but responses to P became larger with time.

The growth of 16 ram lambs was severely restricted for the first 6 weeks of post-natal life. Subsequently, these lambs (group R) were fed ad libitum. The diet was based on reconstituted cows' whole milk and lucerne chaff. A control (group C) of 16 similar lambs was fed ad libitum on the same diet from birth.

Lambs were weighed regularly and, in group C, four lambs were killed at the age of 1 day and then two at each of the following body weights: 10, 15, 20, 25, 30, 35 kg. In group R, five lambs were killed at the commencement of ad libitum feeding (age 43 days) and two each at the same body weights as in group C, except that only one lamb was available at 20 kg. After slaughter, the brain, liver, kidneys and the semitendinosus and gastrocnemius muscles were removed, weighed, stored and, with the exception of the liver, were analysed later for the following components: DNA, RNA and protein. Carcass weight and the weight of the kidney and channel (KC) fat were recorded. The femurs and metacarpals were removed from each carcass and cleaned, weighed and measured.

During the 6 weeks of restricted feeding, group R gained 0·9 kg while the ad libitum group C gained 13·5 kg. However, during recovery, group R grew faster than group C (0·37 ν 0·34 kg/day), reducing the weight for age difference near the end to 29 days at mean body weights of 30 kg.

Because of the design of the experiment, at the same age all measurements on group R animals, after the commencement of ad libitum feeding, were smaller than in group C. For this reason, the interpretation of the results has been based on differences between regression equations relating the various measurements to empty-body weight or to one another.

At the start of ad libitum feeding, brain weight, carcass weight, femur weight and femur length were bigger, while liver weight and KC fat weight were smaller in group R than in group C. At the end of the experiment, there were no significant differences between treatments for these measurements. Metacarpal shape differed between groups, the bone being relatively longer and narrower in group R than in group C, throughout the period of ad libitum feeding.

There were no significant differences between treatments in the relationships between DNA and corresponding tissue weights. However, the RNA was significantly less in both muscles in group R than in group C at the beginning of ad libitum feeding, but this difference had disappeared by the end of the experiment.

The brain protein: DNA and the brain weight: DNA ratios did not differ between treatments nor did they change significantly during the experiment. The semitendinosus was the only other tissue for which protein content was available and the protein: DNA ratio for this muscle differed between treatments, reflecting an acceleration of division by cell nuclei during the recovery period. The other tissue weight: DNA relationships did not differ between treatments and all ratios increased to values similar to those reported elsewhere. RNA:DNA ratios differed between treatments for both muscles, suggesting that high rates of protein synthesis occurred in group R during the recovery period.

In spite of the apparent normality of group R when measurements were related to EBW or tissue weights at the end of the experiment, only a long-term investigation would determine whether the weight-for-age difference of the type reported here would persist in adult life.

Two experiments were carried out to evaluate different dosing and sampling regimes for estimating the dry matter intake (DMI) of vegetation by grazing beef cattle. Experiment 1 compared the DMI of a perennial ryegrass pasture by 48 grazing beef cattle dosed with C32n-alkane and faecally sampled at different time intervals. The cattle, of dairy and suckler origin, were balanced by origin and allocated to one of three alkane-dosing treatments (n=16): T1, dosed once daily (10.30 h) with two 500 mg boluses of C32 alkanes; T2, dosed twice daily (09.00 and 16.00 h) with a 500 mg bolus of C32n-alkane; and T3, dosed twice daily (07.00 and 19.00 h) with a 500 mg bolus of C32n-alkane. Faecal samples were collected concurrently with dosing in each treatment. Dosing interval had no effect on estimated DMI, when calculated using the n-alkane content of faeces sampled concurrently with dosing, suggesting that once-daily dosing with concurrent faecal sampling is adequate to estimate DMI by beef cattle. The objective of Expt 2 was to compare the accuracy of herbage DMI estimated using a once-daily C32 alkane dosing regime and n-alkane concentrations in faeces sampled at 09.00, 13.00, 17.00 and 21.00 h, against DMI measured directly. Twelve Holstein-Friesian bulls (mean body weight 265 kg) were housed individually in digestibility stalls and offered harvested perennial ryegrass or harvested semi-natural upland vegetation, both ad libitum. The DMI estimated by once-daily dosing with n-alkane and concurrent per rectum faecal sampling did not differ significantly from the directly measured DMI for either herbage type. It is concluded that a once-daily alkane dosing and concurrent faecal sampling protocol is adequate to reliably estimate the DMI of both upland and lowland pasture vegetation by beef cattle.

1. Records collected on the steers reared during the long-term experiment on beef production on the Cambridge University Farm from 1946 to 1955 have been analysed to examine the relation of live weight to various body measurements and the dependence of these relations on breed, treatment and age.

2. Among the measurements considered singly, chest girth was most closely related to live weight.

3. There were marked differences in the slopes of the regression lines relating log live weight to log chest girth during the two phases of the experiment—from birth to 8 months of age and from 8 months to slaughter.

4. The regression coefficients in the first period were affected by the treatment on which the calves were being reared. Those in the second period were affected both by the level of feeding the steers were receiving during that period and by the manner in which they had been reared to 8 months.

5. Height at shoulder was the measurement which, as a second variate in the regression equations, led to the greatest increases in the accuracy of prediction of live weight. However, the relation of this measurement to live weight was also affected by the treatment.

6. It was considered that these measurements show little promise as estimators of live weight which could be generally applied, since their relations to live weight were affected by the treatment of the animal.

Aspects of the photoregulation of phenological development in bambara groundnut were studied in a glasshouse experiment in The Netherlands. The influence of a 14 h photoperiod (which retards podding) during a period of variable length prior to an 11 h photoperiod (which induces podding) on flowering, yield and on the position of pods on the plants was determined. The third generation of three plants of genotype ‘Ankpa 4’ from Nigeria was used as the split-plot factor in a split-plot design with three replicates. The main plots were four daylength treatments: a period of 21, 28, 41 or 54 days under the 14 h photoperiod before transference to the 11 h photoperiod. Plants transferred after 28 or more days started flowering sooner the earlier they were transferred. Plants transferred after 21 and 28 days began flowering at the same time (51 days after sowing), thus indicating juvenility. At harvest, 135 days after sowing, the total seed dry weight per plant was higher for plants transferred after 41 and 54 days than for plants transferred after 21 days. Plants transferred after 28 days gave an intermediate value. Most (79–91%) pods were produced on branches that developed on nodes 1–4 of the main axis. There were no differences in the fractional distribution of the pods along the main axis in plants transferred after 28 or more days. Pods of plants transferred after 21 and 28 days were more evenly distributed over the nodes of the first two primary branches than pods of plants transferred after 41 and 54 days. Plants of the latter treatments produced their pods more towards the tips of the branches and concentrated on two neighbouring nodes (nodes 5 and 6 for plants transferred after 41 days and nodes 6 and 7 for plants transferred after 54 days). Delaying the induction of podding in this experiment therefore resulted in higher seed yields per plant and a more synchronized development and hence maturity of pods.

Genotype–environment interaction and yield stability were evaluated for 19 genotypes of lovegrass (Eragrostis curvula). The study was conducted in the central semi-arid region of Argentina. Three locations and two growing seasons in combination generated six environments. Genotypic responses and stability of yield under variable environments were investigated. The genotype–environment interaction was analysed by three methods: regression analysis, AMMI and principal coordinates analysis (PCO). Analysis of variance showed that effects of genotype, environment and genotype–environment interaction were highly significant (P < 0·01). The genotypes accounted for 20% of the treatment sum of squares, with environment responsible for 65% and interaction for 14·5%. The biplot indicated that there was partial agreement between the AMMI and regression model. However the scatter point diagrams obtained from PCO analysis revealed only limited agreement with the results obtained by the regression analysis and the AMMI model. The results show that the AMMI model as a whole explained twice as much of the interaction sum of squares as did regression analysis and was more adequate than PCO analysis in quantifying environment and genotype effects for forage yield. AMMI analysis of the genotype–environment interaction effects showed that there were responses characteristic of a particular location. This type of association implies some predictability of genotype–environment interaction effects on forage yield production when differential responses across genotypes are associated with locations. Environmental factors may contribute to the interpretations of genotype–environment interaction. However in the semi-arid region, where fluctuations in growing conditions are unpredictable, additional research is required to obtain an integration of interaction analysis with external environmental (or genotypic) variables.

The molecular mechanism underlying the yellow seed trait has been a subject of quality breeding in Brassica. Thus, uncovering the biosynthetic pathway of proanthocyanidin (PA) accumulation in the Brassica seed coat is a promising research programme. Arabidopsis thaliana BANYULS (BAN) encodes anthocyanidin reductase, which is involved in seed coat pigmentation. In the current study, 2 and 4 BAN homologues were isolated using one pair of primers from Brassica nigra and Brassica juncea, respectively. Reverse transcription polymerase chain reaction (PCR) analysis showed that BAN was expressed abundantly in the seed coat of black seeds and in the embryos of all lines, but not in the seed coat of yellow seeds. Primers incorporating B genome-specific nucleotide variations were designed according to previously published BAN gene sequences of Brassica species to discern the BAN sequence located in B genome origin of Brassica using allele-specific PCR amplification. Proanthocyanidins were also detected by p-dimethylaminocinnamaldehyde staining and a butanol–hydrochloric acid (BuOH–HCl) colorimetric assay in the seed coat of black seeds, but not in the seed coat of yellow seeds. Anthocyanins were not also detected in the seed coat of Brassica species by the BuOH–HCl assay. Both transcriptional and chemical analyses suggested that BAN genes could be involved in both the biosynthesis of PAs and colour formation in the seed coat of Brassica species, whereas no expression of the BAN gene could block biosynthesis of PAs in the yellow seed coat.

Sixty-four lactating buffalo cows (24 normal cycling, 8 pregnant and 32 repeat-breeder), selected from two buffalo farms near Cairo during 1987 and 1988, were studied during thefirst 26 days after oestrus (day 0). Plasma progesterone concentrations were significantly (P < 0·01) higher in pregnant than in cyclic (between days 3 and 5) and repeat-breeder (between days 0 and 8) animals. Concentrations of total unconjugated oestrogens were also highest (P < 0·01) in the pregnant group between days 6 and 16. Cyclic and pregnant cows had higher (P < 0·01) concentrations of plasma calcium between days 3 and 7, inorganic phosphorus at all times and glucose between days 2 and 8 than repeat-breeders. Plasma protein concentrations were greater at all times, except between days 6 and 8, in the first two groups. Analysis of the uterine fluid collected from cyclic and repeat-breeder buffalo cows revealed that concentrations of all biochemical components, except for calcium, were significantly (P < 0·01) higher in flushings from the uterus of cyclic animals than from repeat-breeders at alltimes for inorganic phosphorus, between days 6 and 12 for glucose and on day 2 as well as between days 8 and 12 for protein. Large differences were found in calcium levels, especially on day12 when flushings from repeat-breeder cows contained more than six times the concentrations of this metabolite in uterine flushings from cyclic animals. The results suggested that reduced luteal function, related to atypical profiles of plasma biochemical components, during the oestrous cycle in repeat-breeder buffalo cows might provide the basis for altered syntheses and secretions of uterine calcium, phosphorus, glucose and proteins which are needed for embryo development.

1. The quality status of Danish and English Wiltshire bacon sides representative of the highest grades produced at the present time has been investigated by the use of carcass measurements. The data resulting provide “standards” for practical guidance in stock improvement work on bacon pigs, and for the evaluation of experimental treatments involving bacon quality.

2. The variability of the respective characters has been compared by means of the coefficient of variation of each. The results indicate that while selection on a basis of “external characters” and of such internal characters, as are readily measurable, leads to marked uniformity in respect of these characters, it does not necessarily involve similar uniformity in respect of important “internal characters” which are not taken into account in either stock selection or commercial grading practices.

3. External characters thus do not provide a reliable indication of the internal quality status of the bacon pig, and since it is the latter which largely governs the cutting value of the side, concentration upon addition to the former is desirable if still further improvement in the quality of the bacon pig is desired.

4. Variability appears to be affected also by the rate of development of the character concerned; late developing characters in general tend to be more variable than early.

5. The intimate association between nutrition and the rate of development of the various parts and tissues of the pig provides a method of control in addition to that of selection.

Genetic parameters were estimated for purebred and crossbred lambs of a local breed using a single trait animal model. The traits recorded were: birth weight (BWT), weight at 30 days (WT30), weaning weight (WWT), average daily gain from 1 to 30 days (ADG1) and average daily gain from 30 to 90 days (ADG2). Five different animal models were fitted for each trait; all including additive direct genetic variance and various combinations of additive maternal and environmental maternal effects. The most appropriate model was chosen based on likelihood ratio tests. Additive maternal and permanent environmental effects were important (P < 0·05) for birth weight in purebred and crossbred lambs, when compared with a model containing only additive direct effects. Inclusion of maternal permanent environmental effects provided a better fit (P < 0·05) for weaning weight in purebred lambs than a model containing only additive direct effects. Estimates of heritability from the model containing additive direct, maternal effects and maternal permanent environmental effects, but not additive direct-maternal correlation, for combined purebred and crossbred lambs were 0·32 for BWT, 0·19 for WT30, 0·24 for WWT, 0·26 for ADG1 and 0·12 for ADG2. Estimates of additive maternal and maternal permanent environmental variances, respectively, as a proportion of phenotypic variance were 0·06 and 0·07 for BWT, 0·05 and 0·02 for WT30, 0·02 and 0·03 for WWT, 0·03 and 0·05 for ADG1 and 0·00 and 0·03 for ADG2. Estimates of direct-maternal correlation in subsequent analyses were significant and ranged from −0·16 to −0·95 for live weights and from −0·73 to −1·0 for daily gains. However, the very large negative correlations probably resulted from undefined non-genetic covariances as well as possible antagonistic genetic effects. These results indicate that it would be possible to improve growth traits in a local sheep breed through genetic selection.

Although the grey forecasting model has been successfully employed in various fields and demonstrates promising results, the literature shows that its performance could still be improved. Therefore, the aim of the present study was to continue the investigation and derive three hybrid models to predict grain production in China by combining particle swarm optimization (PSO) with the grey linear power index model, the grey logarithm power model and the grey parabola power model. In grey modelling, the use of PSO had the ability to search optimum grey parameters to construct three improved derivative grey models. The results concluded that the improved optimization models with high precision were superior to the traditional models, and PSO contributed more to precision improvement of the three grey models. Furthermore, results from the experiments demonstrated that the optimized models were reliable and valid.

The interacting effects of genotype and density on the yield of dry matter by mature shoots were examined at Oxford, England. There were six hybrids, either pure dent or flint × dent crosses, together with two open-pollinated flint varieties of very early maturity. Over a range of 15 densities (5·0–30·8 plants/m2) for all the genotypes the relationship between the yield of the shoot and density can be adequately described by the reciprocal equation 1/w = A + Bp, where w = weight per plant, p = number of plants per unit area and A and B are constants for any particular set of conditions. Values of both 1/B (asymptotic yields) and 1/A (weight per plant at very low densities) were dependent upon the genotype. In a regression analysis between 1/w and p, the variance of 1/w was over 40 times as great at high as at low densities and a weighted analysis was necessary. Some hybrids approached maximal yields at 5 plants/m2, whereas others required a density of 10–15 plants/m2. The possible reasons for these interactions are discussed and improvements in experimental design suggested.

1. The relation between the soluble-nitrogen content of grass silage and the pepsin digestibility has been investigated, and formulae have been derived for calculating the protein digestibility in the silage dry matter from the determined solublenitrogen content.

2. Comparisons have been made between the calculated results for protein digestibility, the results using the formulae of Watson and Dijkstra and the digestibility as determined on sheep.

3. The peculiarities of molassed silage in the above connexion have been noted.

In studies of the seasonal distribution of nitrogen fertilizer dressings on grassland using conventional experimental designs it is usually not possible to separate the true effects of an individual fertilizer dressing on the yield at a particular cut from the residual effects of previous dressings. An experiment is described which was designed to allow separation of the direct and residual effects, with certain restrictions, for a system involving five cuts and five possible fertilizer dressings per season on perennial ryegrass swards. From the results obtained over two harvest years on swards on two adjacent sites equations were derived relating the dry-matter and crude-protein yields of herbage to the rate of nitrogen application at five dressings in the season. Predictions of yield distribution patterns from the equations are compared with observed yields from various sequences of nitrogen dressings included in previous experiments at this Institute. Examples are also given of the prediction of sequences of nitrogen dressings required to obtain certain patterns of yield distribution.

Bunaji and Sokoto Gudali breeds of cattle were fattened and slaughtered at live weights of 250, 300 or 350 kg. After the carcasses were jointed into commercial cuts, the joints of the left side were dissected into lean, bone and fat. Dressing percentage was significantly higher in Bunaji carcasses (52·5%) than in Sokoto Gudali carcasses (50·3%). The lean percentage was nearly constant at 68·69% at all slaughter weights whereas fat percentage increased from 10·3 at 250 kg to 14·5 at 350 kg. Bone percentage was inversely related to fat percentage. The relative growth coefficients of muscle and fat were 1·28 and 1·80, whereas that of bone was 0·59. Significant changes in proportion of carcass parts and tissues were observed with increased slaughter weight. The proportion of hind decreased and that of back and belly increased, while chuck and shank remained relatively unchanged. Lean percentage was relatively unchanged by slaughter weight in all carcass parts except the chuck where it increased. The greatest increase in fat percentage was in the belly (7·6%) followed in decreasing order by the back (5·4%), shank (4·9%), hind (3·0%) and chuck (1·8%). The breeds did not differ in any of the traits except dressing percentage.

Four experiments were conducted in the Yucatán, Mexico, in 1991 and 1992 to study feed intake in 24 h trials with chicks and pigs fed diets containing either raw or treated jack beans or conventional diets with added canavanine.

Feed intake of chicks in the first hour was markedly reduced and feed intake of pigs was severely reduced when raw jack beans (300 g/kg for chicks, 250 g/kg for pigs) were included in their diets. Feed intake of pigs diminished to a greater extent than that of chicks when treated beans (300 g/kg) were included in the diet. Short-term feed intake of chicks was not affected when canavanine (3·5 g/kg) was added to a sorghum-soyabean diet. However, pigs showed a large drop in feed intake when canavanine was added to a maize-soya diet at only 0·8 g/kg. It was concluded that in both species the anti-nutritional factors in jack beans cause a rapid reduction in feed intake which precedes a depression in growth rate. The initial feed intake depression in pigs could be partly attributed to canavanine remaining in the jack beans after treatment. In the chicks' case, however, rejection of a diet containing treated jack bean was due to anti-nutritional factor(s) other than residual canavanine.